I booked a trip for the family on a 3-class 777-2, CW on a leg and WT+ on the other.

To be able to sit 3 of us plus an infant together, I picked rows of 4 with bassinets: Row 4 DEFG in CW and Row 12 DEFG in WT+. There are 2 seats with bassinet on these rows, for example in WT+ cabin they are 12E and 12F.

When I try to sit the 3 of us in 12DEF, the system won't let me pick E and F as I only have one infant! As a result I had to pick 12DE and G, leaving the middle seat 12F, another bassinet position, empty!

Wondering what will happen when we board, will the system sensibly reallocate us into 12DEF, or will a surprised and grumpy passenger end up in 12F in the middle of our family? Yes, we would offer to swap at this point, but still, it seems a quirk of the advance seating arrangements.